Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#ifndef _LINUX_VIRTIO_RING_H
2#define _LINUX_VIRTIO_RING_H
3
4#include <linux/irqreturn.h>
5#include <uapi/linux/virtio_ring.h>
6
7/*
8 * Barriers in virtio are tricky. Non-SMP virtio guests can't assume
9 * they're not on an SMP host system, so they need to assume real
10 * barriers. Non-SMP virtio hosts could skip the barriers, but does
11 * anyone care?
12 *
13 * For virtio_pci on SMP, we don't need to order with respect to MMIO
14 * accesses through relaxed memory I/O windows, so smp_mb() et al are
15 * sufficient.
16 *
17 * For using virtio to talk to real devices (eg. other heterogeneous
18 * CPUs) we do need real barriers. In theory, we could be using both
19 * kinds of virtio, so it's a runtime decision, and the branch is
20 * actually quite cheap.
21 */
22
23#ifdef CONFIG_SMP
24static inline void virtio_mb(bool weak_barriers)
25{
26 if (weak_barriers)
27 smp_mb();
28 else
29 mb();
30}
31
32static inline void virtio_rmb(bool weak_barriers)
33{
34 if (weak_barriers)
35 smp_rmb();
36 else
37 rmb();
38}
39
40static inline void virtio_wmb(bool weak_barriers)
41{
42 if (weak_barriers)
43 smp_wmb();
44 else
45 wmb();
46}
47#else
48static inline void virtio_mb(bool weak_barriers)
49{
50 mb();
51}
52
53static inline void virtio_rmb(bool weak_barriers)
54{
55 rmb();
56}
57
58static inline void virtio_wmb(bool weak_barriers)
59{
60 wmb();
61}
62#endif
63
64struct virtio_device;
65struct virtqueue;
66
67struct virtqueue *vring_new_virtqueue(unsigned int index,
68 unsigned int num,
69 unsigned int vring_align,
70 struct virtio_device *vdev,
71 bool weak_barriers,
72 void *pages,
73 void (*notify)(struct virtqueue *vq),
74 void (*callback)(struct virtqueue *vq),
75 const char *name);
76void vring_del_virtqueue(struct virtqueue *vq);
77/* Filter out transport-specific feature bits. */
78void vring_transport_features(struct virtio_device *vdev);
79
80irqreturn_t vring_interrupt(int irq, void *_vq);
81#endif /* _LINUX_VIRTIO_RING_H */